how can YOU (the consumer) or you (me, in the field) tell?
YOU can't easily tell. I can't tell without popping that lower door off. All it takes is a key and a 3 second peek, if you have one. Racetrac (Raceway, now?) Speedy Stops, Murphy USA (Walmart gas), etc, will all use filters. Major brand chains.
You could also ask the attendent (non-chalantly) if they hate changing the filters on their own... if they do it, they'll very agitatedly say "YES!" if they don't have them, (or have a company do them) then they'll like say "uh... what?" or "HAHA.. luckily we have someone do that for us!"
You can feel the responses for your own determination.
